At present, most of the energy storage systems are activated and operate only in case of power interruption or when there is a need to use it. Under normal circumstances, the energy storage system is in an off-working state, in which the energy storage system is required to consume no power or consume as little power as possible. The energy storage systems at present mostly operate in the following two modes. In a first mode, a mechanical switch is adopted. When the energy storage system is not required, the mechanical switch is turned off and the energy storage system does not work at all. This mode suffers from high cost, and especially in large-current situations, the mechanical switch are quite expensive. Moreover, the problem of delayed response and cumbersome operation exist. A second mode is a direct standby mode. In this mode, a single auxiliary power supply is adopted, the standby power consumption is high, causing great energy loss, thus increasing the number of charging and discharging cycles and affecting the life of a battery. Therefore, there is a need for designing a new switching control method for a dual auxiliary power supply.